This invention pertains to rotary liquid pumps, such as vortex-type cooling pumps used, for example, with marine diesel engines, and to an impellers and shaft assembly for Such pumps as well as to flexible-impeller pump assemblies.
Existing rotary, self-priming, liquid pumps, having flexible impellers, which self-prime when dry, are capable of pumping up to one hundred and twenty-five gallons of liquid per minute, and such are suitable for use with marine diesel engines, or the like, having up to about twelve hundred horsepower. At engine speeds of from approximately twenty-one hundred to twenty-five hundred revolutions per minute, larger flexible impeller pumps will cavitate under such circumstances. There has been a long standing need for a rotary, self-priming, liquid pump having a capability for handling flow rates up to about four hundred gallons of liquid a minute for use in cooling engines of up to about twenty-five hundred horsepower. Too, then, there has been a collateral need for a novel impellers and shaft assembly for the aforesaid, needed, greater-capability pump, and an improved flexible-impeller pump assembly for pump priming and other uses.
In the prior art there are regenerative-turbine and/or side-channel, water ring pumps which comprise the equipment presently available for marine diesel cooling. However, such are very inefficient, the efficiency thereof being in the order of twenty-five percent. These prior art pumps cannot self-prime when absolutely dry, and must have impeller clearances of approximately 0.006 to 0.010 inch in order to insure that they will operate at all. Such fine clearances make these pumps difficult and expensive to manufacture, and they have a low tolerance for sand and debris. More, the known pumps have a high, radial, hydraulic loading on the impellers, due to the differential pressure thereacross; this can occasion broken shafts, seal leakages, and bearing failure.